Production of motor fuel



Patented Sept. 18, 1945 PRODUCTION OF MOTOR FUEL Gilmore T. Gwin, Baytown, Tex assignmto' Standard Oil Development ration of Delaware Company, a corpo- No Drawing. Application December 1a, 1942, Serial No. 409,453

3 Claims. (CL 260-6834) The present invention is directed to the production of an improved motorfuel from low boiling hydrocarbons by alkylation.

In the production of high-quality motor fuels, in particular, gasoline fuels particularly suitable for use in airplane engines, abundant use has been made of the well-known alkylation process. The alkylation process refers broadly to the reaction between an isoparafllnic hydrocarbon and an olefinic hydrocarbon, usually in the presence of a suitable catalyst, to produce an isoparaflinic hydrocarbon product which is of especial value as a constituent of aviation gasolines on account of its high resistance to motor knock and its appropriate volatility and boiling range characteristics. A well-known and widely-used example of the allwlation process is the reaction between isobutane and a butylene, such as butylene-2, using concentrated sulfuric acid as a catalyst,- to produce isomeric, paraiiinic octane hydrocarbons, including 2,2,4 trimethyl pentane. Instead of isobutane, other isoparaflinic hydrocarbons, such as isopentane, can be used. Pentylenes, propylene, and many other oleflnic hydrocarbons can be used in place of the butylenes. A wide variety of suitable catalysts are also well-known.

The alkylation reaction, in its application to the art of petroleum refining, does not follow quantitatively the pattern of a simple stoichiometrical equation. For example, when a C4 isoparafiln such as isobutane is alkylated with a C4 olefin such as butylene-2, the product is not a singe isoparaflinic Cs hydrocarbon, nor is it entirely an isomeric mixture of Ca hydrocarbons. It has been recognized that other reactions also occur, resulting from a scission in one or more of the carbon-to-carbon linkages, to produce iso-- parafiinic hydrocarbon compounds other than Cs hydrocarbons. These reactions may be termed fragmentation reactions. The extent to which these side reactions occur has been observed to vary with the operating conditions employed, such as temperature, ratio of reactants, and contact with catalyst, and also with the specific nature of the reactants. Many other hydrocarbons, such as isopentane and the pentylenes, have been observed to be more susceptible to producing side reactions, or fragmentation reactions, than are the Ci hydrocarbons cited above.

Isobutane has been found to be the most desirable isoparaflinic hydrocarbon for use in the alkylation process hereinbefore described, on account of its inherent chemical reactivity and on account of the fact that its use results in a prodpoint of anti-knock characteristics and boiling The butylene hydrocarbons .have.

be the most desirableoleflnicrhyw drocarbon constituents for the alkylatiomreacpoint range. been found to tions, largely for the same reasons; The pentylene hydrocarbons function quite ess, and are widely used.

Recently, other important industrial uses for 3 the isobutane and butylene hydrocarbons have been developed. For example, it has been found dehydrogenated to bons for the isobutane and butylenes commonly. f

employed in tylene hydrocarbons are place the butylenes as the oleiinic component in degree. It would also be desirable, under certain conditions of limited availability of raw materials, to replace or augment the isobutane with another isoparaflinic hydrocarbon such as isopentane. An'objection to. the use of isopentane is that it does not function as well as isobutane in the alkylation reaction. For example, it has been found that when isopentane is alkylated with pentylenes, using the familiar sulfuric acid catalyst, the product is definitely inferior to that obtained with isobutane and pentylenes, with reference to subsequent use as a component of high quality aviation gasolines. It is inferior for the foiiowing principal reasons: (1) It does not have as high a resistance to motor knock; and (2) a relatively large portion of it has too high a boiling point to permit its use in high quality aviation gasolines. It has already been suggested in the prior art to utilize the alkylation reaction to separate isopentane from refinery C5 cuts containing it in association with pentylenes and normal pentane. Such a process is described and claimed in U. S.

the alkylation process. The penalready being used to rehydrocarbon 2,264,447. The refinery Cs cuts with which this patent is concerned usually contain substantial amounts of isopentane, but larger amounts of; amylenes. A typical refinery C5 cut, for example, might contain about 28% of isopentane and 35% of amylene. The patentee points out that, in recovering isopentane from such a fraction, another isoparailln, such as isobutane, is added to the C5 cut and the mixture subjected to alkylation. The patentee prescribes the employment of a large excess of added isoparailin to olefin, by

net or unusually hi h quality t t d. the maintenance of a-hien ratio of recycle to satisfactorily 1 as an olefinic feed stock for the alkylationprocthe alkylation process to a large 2 asamss.

feedstock and-a ratiotof at least2':1 and preferably to 1= the order: of: 10:11 of added. isoparaifln to olefiirtin: the;.-i5reshfeedi This combination of measures would. normally result in the maintenance of a ratio. of:added isoparaflln. to olefinin the actual reaction mixture considerably'in excess of :11. Thismeans, of. course,,v that; there would. be 'even'agreat'erratio ofiaddedxisoparaflin to isopentane in; the reaction mixture.

Theepresentfinventlon:isbasedionthe discovery that whens. minturerof isobutane: andisopentane containing: a substantial amount of isopentane,v

such as-eataleast 30 is em-ployed:in the alkylation reactiom. a1 products. is obtained which is: greatly superior tQ-thati which: could have. beeneXpected' from the icharacteri'stics'of. the products oliitalnedv byvalkylating; thesezis'oparafllns separately under the same: conditiona Furthermore, the: product?- obtained fromz the: mixed isoparam'nic teed. is considerably; superior: tox'thatrobtained' byblendingzthe; products; obtained by; separate" alkylation; i

of therindi'vidualiisoparaflinscunden-thezsame con" ditions-iin therfblltrwiirgrespectsrt or) The product from the mixed i'soparafllnic. teedhasz a. higher octaneinumberthanr the: blend from the products.

of T the individuali isonariatfli'ns. (2'), The. productfrom.the mixediisoparafllnicsfeed containsahigher percenta'gmof material boiling. in .the tempera-- ture-rangadesirableior an aviationigasoline than the blend of "therproduct's from the' individualzisoparafllns. In. making the: latter statement; the

fraction of a'llylate particularly. suitable .tor aviation gasoline; has: been taken, to 'be that'pm'tionof? the total? depentanizedallrylatetzboiling: below:

therblendi mentioned herein above it. is. un-& derstoodithattthe ratio-of the two products in the blend'i's-in'; the-same ratio ascare the :quanti'tiescf the individual: alkylates produced from-each of the isoparafllnssinzthemixed'feedi The improved. results which can: be obtained wheni'usinga; mixed" isoparaiiinic: ieeci stockv in accordance? witha-the. present; invention; 'may be; illustrated by the following, results of runs; usingr as theisop'arafllnic feedystoc krespectlvely'(l'l' isobutane,.(2) isopentane, (3) a mixture of lsobutane: and isopentane in equal molar ratio. A pentanepentylene stock was used as'the olefin feed stock ineach-run; The same operating'conditions were used. in-eachrunand were as follows: volume ratio ofIisoparaflins to-olefins, 7:1; temperature 40 catalyst,'.95l%' commercialblacksulfurlc acid; /2

volumeof: acid per; volume-of totalf hydrocarbon; average time: 01 contact; one. hour. yIt may be observed that these runs were madein a." system operating: .on: the emulsion-type" principlewell. known.inzth'eliterature. The pertlnent 'resuits of. these runsiwereas follows:

Inspections on IBP-320?" F. traction of dopenta- I nized'zalkylate product Isopareflln stock'used V v I Volume per 123%? centol total alkylate Isobutane; 91.0 on lscpentane; 81. 9 80:2 lsobutanevisopeniane (lit-mole ratio) L 87." 9 92. 3

In therun. employingthe. mixturesof 'isobutane and 'lsopentane as the feedstock, .the relative pro portionsofisobutane and; isopentane reacting to produce alkyiate were determined; in the follow-' ing manner. The feedstock and the reaction: product" were each carefully analyzed for isobutane' and isopentane content. according to the.

method .of Podbielniak. In thisway. the; quantities of isobutane and isopentane" which were -con:-- sumed. inz the course of. the reaction were: determined; It was also determined: independently that" when isopentane alone is alkylated: with; pentylenes under the same conditions,.isobutane= is actually' produced in the average quantityci'. 0.3 mole: oft lsobutane permole of isopentane re- 1 acted-.1 Allowance was madefor-this-productionioti isobutanezincalculatingthe quantity ofqisobutanereacting. to produce xalkylate; according. to the procedure 'hereinbefore described. In this manner; it was found. that, in: the run 'describedlabove; us-

ing a mixediisoparafllnic feed ,isobutane: undiscpentane: were; actually consumed: in. the rea'ctiona to produce. alkylate in the IatiOi of; 0l67 1; or; two

partsof isobutane. to. three pa1tts of; lSODElltBIIE4.

The-.alkylatesproduced from the. isobutaneaand' isopentane individually were blended togetherwin'.

the above ratio of production. An inspection: of

the-IBP.320 F. fraction of this blend: after dc pentani'zation showed an ASTM-octane number.-

of'85;6;. Thisfraction constituted 85.4- volume-per.

cent of'the total blend. Thesedata compare unfavorably. with the ASTM octane numberzor' 8739; and thevolume' per cent oftotal alkylate:of"92.'3f shown above'tor the alkylation-run employing the mixediisoparafllnicfeed stock.

While the isobutane and i'sopentane were present. in-equal'molar concentration inthe run de-- scribed above, it is not to be assumed that thisratio is essential to obtaining-animproved result; over the alkylationv offthese, isoparafiins individ- 'ually. In any case to obtain the particular de- 'sirable featuredisclosed'herein the proportion.- of.: isopentane should not be less'thanabout130% of? the total isoparafllnic feed"; When. smalleramounts of. isopentane' are employed;v the olefins tend toreact with the isobutane' to theexclusion. oi the isopentane. An excess of isopenta'ne over:

isobutane' within certain limits'is desirable. For. example, three parts of isopentane to two parts of' isobutane makes a very'satisfactory isoparafilnic feed.v If the isopentane constitutes more than 70% of the isoparaifinic leed, the" quality of the 7 product'sufl'ers;

' The nature and obiectsof the present invention having been thus described and illustrated, what secured by Letters Patent is:

1. A process for alkylating isoparaffins withole fins in the presence or a suitablecata'lyst' which 7 includes the step of chargingan isoparafllnic teed comprising two lsoparafilns having a difierent' number 0! carbon atoms in their molecules in which neither'isoparaflln constitutes less than 30 moleper cent of the total isoparafllnic feed.

2. A process accordingto claim 1.in which the isoparafllns are isobutane and isopentane.

3. A; processrfor alkylating. isopentane with an olefln..in. the presence of a suitablescatalysttwhich includes the step of adding to thezisopentanea substantially equal molar amountrof isobutane;

GILMORE T. GWIN.

is claimed as new and usefulanclisdesired to be 

